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1,637,401 2, 1927- c. s. \NEYANDT METHOD OF AND MEANS FOR CONTROLLING RECIPROCATING MOTORS Filed March 1924 2 Sheets-Sheet 1.

22 o o m 24 28 20 um- I I J as 6/ 7 5 E 2% 6a v 1,637,401 A118 2, 1927- c. s. WEYANDT METHOD OF AND MEANS FOR CONTROLLING RECIPROCATING MOTORS Filed March 1924 2 Sheets-Sheet 2 Patented Aug. 2, 19 27. v

entree stares fearm" OFFICE.

CARL S. WEYANDT, OF PITTSBURGH. PENNSYLVANIA, ASSIGNOR 'lO CENTRAL ELEC- TRIC TOOL COMPANY, A CORPORATION OF TENNSZ'LYANIA.

METHOD OF AND BEE/ANS FOR CONTROLLING RECIPROCATING MOTORS.

Application filed March 5, loge. sena1 1i o.re7,os4.

' This invention relates to reciprocatin hammers'to iilarocnre a.r ecip rocating 'inoir eelectric motors and particularly to a method menti th'e core'; itrchingbt'yi een theco n:

ofand means for controllingthe same. tact sur ac s ha s alivays necessitatedgiving fOne'obje ct of my invention is to pro "derable:parefandlattntion to'thejsivitch ling an'electric hammer of the reciprocating QJ AQ IO bj c jif my in ention has.,l eeri motor t jpe,j .whereby the necessity for obviate the;dlcadi anta-gesiinlirent infa' sysswitching deriees, that comprise contact (er:- 'c'n'iploj'ing switching devices tocon? members susceptible to arcing duringthe trol the operation of an, electric hammer.

x0 cperiitioirot a hannner, shall beobviated. Ins fad ot la; switcliing' deviee embodjing HQA iiother objectofniy inventionisto 1510- c n'tfic cs su lgjcttoand susceptibl ride an electric {hammer system in which frcin nl'pr ride i11en-1'c j' 3 m1 onl one part or element shall be in motion tor or electric ralvemomprising stilti if iy during the operation of the hammer, viz, terminals, or electrodesfor o tr lli g-th 15 the striking or impact element. rg iri of. the hammer opera windlAno ther objectof. my invention is to proing .W hen conp ec tecl 'be tweenuann t' f p ride a system for controlling a reciprocating trig. cuirentei'rcuitendithe li inmeronly curmotor. that shall comprise a closed circuit rent firay es' of;predeterminedpolarity :are whereby all energy stored inmagnetic flux transnnttedgfir}, in 'some instances, ,depend- 20 fields shall beutilized to d0usefn l, Work iningupon; the nature 'of lthenizjaliteconlyiprestead otbeing permitted to dissipate, as ponderatingly umdirection al curi i t 1 hem. in arcing between sepaieting contact pulses. Allarcing is'f 'thus obvi ated and all surfaces. j energy is rendered available-forusefulqiforlc.

In the electric hammer which I employ lvhenapplied to'a s'ystleino fthe character and'control in accordance witlit he princi here considered, .the electric .valveis particuplesf ofmy intention. I provide i1" barrel or 1a rl'y adrraiitageous. .Anele'ctric liammeris guide of non-magnetic material as a guide h g bf ductii/e and the inductanceyaries for room in a solenoid which constitutes the as the core reciproe ate s. Moreover, consideractuating winding. of thewmotcr or hammer. ahle efnergfisstored in the magnetic field :;a In order to reduce the reluctance of the magestablished in sueha device. In aswitching.

neticircuit, and to concentrate the magnet c dc c, sucln as a mechanical rectifier, thefiurc developed In the actuating 'windin I switching operation could not always be ef- 8 provide a plurality of laminations of 'sulr Acct- 3 a: zero current alue. ifter the sta'ntiallr C shape comprising two end porswitching operation which opens the circuit :1: tiozls separated to form an air cap. The of the lzannnecmaiir winding, the energy lamination; are disposed. around the solestored in the magnetic field must dissipate nnid. or winding. with the air gap adjacent itself in some n \Then a mechanical the side of th lam-rel and opposite the midhing dcrice is employed. the energy dle region of the winding. The tips extend patcs itself in the arcin between the 4o thro 1 openings in the barrel to within a contact surfaces, merclyas heat. flVhere an few thonsandths of an inch from the inner electric rairc is employed. however, the cirsnrface of the barrel engaged by the moving cult is not opened and the complete current core. "By reason of the tips being disposed energy impnlseis transmitted to do useful very close to the core, leakage flux is reduced \-.--rk.;.. gy Stored In the g e 45 to a minimum and substantially the comtieldris not now wasted as heat but is transplete magnetic flux is concentrated upon the formed into useful energy. 7 core to actuate it in either. direction. l-Vith The electric valve, moreore r,"is automatic this construction the eth'ciency of the motor in opel'atio'n. (Such a .valve is responsive is considerably increased over that heretoto the polarity of 'the current traversing-a 50 fore obtained. circait including the valve, and, automati- It has been customary, heretofore, to use call by electrical action, rendersits circuit switching dcr'ces for supplying current im- (01:11 active or non-conductive to currents of pulses to the operating windings of electric ne 15: the other polarity that may be derived from an alternating current circuit. The electric valve docs not-arbitrarily control the conductivity of a circuit and the transmission of current at a definite time, irrespective of the character of'the'current, as the mechanical rectifier does, but instead, controls the circuit conductivity and current transmission automatically in accordance with the current polarity.

Electric valves of different kinds may be used. The familiar vacuum valve, commonly used for battery charging and comprising an electron emitting body, such as a heated filament, asthe cathode and a plate as the anode, is particularly suitable for this application. It is light in weight, portable, relatively economical and rugged. Such valve transmits current waves of onl one polarity from a source of alternating 4 current. The energy impulses are separate and distinct.

The mercury valve or rectifier is similar in operation in that it en'ibodies relatively stationary terminals or electrodes, and

'- transmits the complete energy impulse of waves of one polarity only.

The electrolytic valve or rectifier offers the advantages of stationary electrodes although it, transmits preponderatingly unid'irectional current energy impulses rather than impulses composed of a' current wave of only one polarity)" The electrolytic valve transmits, for example, the normal positive current" wave and af'negative wave-of relatively-small value. l'Vjhen such a valve is employed to control an electric hammer, the energy transmitted constitut s; in effect however, unidirectional "current impulses.

Solid reetifiers or valves of the metal type, or of themetal to metal 'typje or of the type in which the elemcnFSurifaCeS are in con tact, which have unidirectional current conducting characteristics also offer the advantages of stationaryelectrodes requiring no attention.

Fig. l, of the accompanying drawings is a diagrammatic view of an electric hammer system containing an electric hammer constructed and controlledin accordance with my invention; I

Fig. 2, is a longitudinal view, partially in section, and partially in elevation, of the hammer illustrated in Fig. 1;

Fig. 3,is .a sectional view, taken laterally, ofithe hammer in Fig. 2;

Figs. 4 and 5 are elevational side and,bottom views of the laminations employed in the magnetic circuits of'th'e hamnjie'r illustrated in Fig. 2; i

Fig. (3, is an oscillogram.illustrating the wave form of current transmitted by the electronic valve in the system shown in I i".

ig. 7, is a longitudinal view, partially in section, and partially in elevation, of the barrel or guide for the core or striking element;

Fig, 8, is a transverse sectional view of the liar-rel illustrated in Fig. Ti;

I Fig. 9, is a diagran'imatic view of a modified system similar to that shown in Fig. l but utilizing an electrolytic valve instead of an electronic valve;

Fig. 10, is an oscillograni illustrating the wave form of current transmitted by the electrolytic valve in the system shown in Fig. 9;

Fig. 11, is a diagrammatic view of a system similar to that shown in Fig. 1 except employing a mercury arc valve. i

The arrangement of the system may be understood upon reference to Fig. 1. Energv is derived irom an alternating current circuit and transmitted through an electric valve 21, .to an electric hammer 22 of the reciprocating .motor type.

'The'electric valve 21 here illustrated is of the electronic type, comprising an electron-emitting element, such as a filament 23,

as a' cathode, and a plate 2 t as an anode. A

transformer 25 supplies energy"to .the filament cathode 23 to render it, incandescent and electron-emitting to establish an operative condition in the valve 21 for transmi t. ting currentwaves of one polarity to the hammer22. The hammer22-comprises, as may be seen in Fig.5.? to 8, inc. operating coil or solenoid 2.6; a movable core 2? controlled thereby, a barrel or guide 28 of non-magnetic material, such as bronze, for the core 27, coaxial'ly' disposed in the coil 26, laminated magnetic circuit cond-uctors' for directing the magnetic.iorcefdylQpgd the coil 26, a casing 3 1,.en'clo,sing the, coilfand the. lamimated magnetic circu t conductors "29 and a ll li tlle' 32 provided with 'a trigger switch 33 ,Eor controlling the 'operation of the hammer. i i I The laminated magnetic circuit conductors 29 comprise two members of L shape 34 having a base portion 35 and a side portion 36, and a straight connecting. member 37.

Some of the L shape members 34 are provided with tips 38 disposed at the ends of the base portions 35, that are adapted to fit tightly in openings 39in the barrel.

'The laminations 29 are arranged in sets as illustrated in Figs. 4- and 5. nThe inner laminations' of each set' comprise these provided with the tips 38 that lit tightly in the barrel. The lamination's thus' serve the twofold purpose of l'ockin' the coil 26 predeterm'i'ned' position re alive to the barrel 2 8 and of directing and concentrating the magnetic flux,.'at' the 'most effective position to influence the core.

The tips 38 extend through the side of the barrel to within a few thousandths of an inch from the inner surface of the barrel 28,

ill)

which'is engaged by the core in its reciprocating movemeuts. 'lhe'relatively short air gap between the tips of each set of laminations reduces the reluctance of the magnetic circuitto a minimum value and insures a highly efficient magnetic circuit. having a relatively small amount of n'iagneticleakage.

The sets of laminations are disposed radially around the barrel 28 and the coil 26, as illustrated in Fig. 3. The separate air gaps of the respective sets together constitute'an air gap of annular shape which is adapted to be bridged or shunted by the core 27 in its reciprocating movements.

The barrel 28 serves as a guide for the core 27 and as a supporting structure for the different elements whereby they may be assembled into a compact unit. The barrel comprises a cylindrical tube ofbronze provided'with the openings 39 to receive the tips of the laminations. 'The forward end ofthe barrel is threaded to receive an open end cap 41 providedwitha'threaded opening within which a tool guide 42 is disposed. Thetool' guide 42 1s provided with an opening within and through which the shank of a tool 43, such as a drill. chisel, rivet set or the'like, may be disposed in the path of'travel'o f the core 27. The rear or handle end 'ofthe barrel is provided with an enlarged flange like cylinder 44 that is externally threaded. The end of the barrel at the cylinder;44: constitutes a. seat 45 for a spring-cushioned backstop 46-. .A spring 47 is disposed between the backstop 46' and a cap 48 which together with the cylinder 44 fits into a recess in the handle The handle cooperates with' the end' surface of the cylinder 44 to secure-the cap 48 in position. The outer surface-of the base of the cylinder 44 joins the; outersurface of the barrel to constitute.ag-shoulder Z49 against which the rear- -laminations'34aare seated.

Although the barrel should be'of non magnetic ,material, any non-magnetic material-will-not besatisfactory merely because of its non-magnetic character. A barrel employedrin'such an application, as a guide for a reciprocatingelement of steel, such as the-core must be, requires, in addition to a nonmagnetic characteristic, physical characterist-icsof hardness, toughness.- and high tensile strength; ,Thebarrel must be hard to resistabrasive action of the core, and mustbe tough andghave a higlutensi'le'st rength to resist stressesset up.-by.- the endyplate ll and the handle 32. in, tightly fsecuring. all the parts asaunit. v

I havel foundthat a bronze barrel having a content of about copper, 39% zinc and from,traces to l% manganese. has the qualities and'characteristics essential for a barrelemployed as a guidein a reciprocating motor on electrichammer. Such a barrel resists abrasive action of a reciprocating core and permits tightly securing all parts to form a compact unit, as is illustrated in Fig. 2.

The respective dimensions of the tool shank and the. core should be such that when one end of the core engages the end of the tool shank. as illustrated in Fig. 2, the other end should be within the path of magnetic influence of the laminations. One end of the core should always be subject to the influence of the magnetic flux at the extreme positions of the core. The backstop 46 should accordingly have such dimensions as to insure that the core will extend into the flux field when the stop is engaged. i

In assembling the hammer the L shape laminations on the right hand or left hand side are first placed in position, in and around the barrel. Two fibre washers 51 are placed around the barrel on the inside of the laminations. The opposite sets of' L shape laminations are then placed in position. A layer of insulation 52 is wound over the surfaces of the base portions of the barrel. between the tips. The insulation 52 serves to hold the L shape lamination s in position while the operating coil 26 is wound on the barrel. and also serves 'to hold the fiber washers 51 in position against the sides of the perpendicular orlateral portions 36. After the coil is wound upon the-barrel, the straight laminated portions 37 are'placed in position and secured to the L-shape portions by suitable means such as rivets 53. The backstop parts are then placed in position andthe'handle is securely threaded onto the barrel. The casing 31 is placed around the coil. the core 27 is inserted through the front end of the barrel and 'the front end capv 41' is threaded onto the barrelto clamp the casing securely between the end cap and the handle; The tool guide is then placed in position so that the plane of the front surface is a predetermined distance-from the front surface of the'backstop; 'he'na tool haviuga shank of predetermined length is inserted through the tool guide. the: core will be'held in the magnetic path when engaging the too] shank. and proper operation'ofthe core will be ensured.

\Vhen operation of the hammer is desired, the trigger switch is closed and connects a relay switch 55 to the circuit 20. The-relay witch 55, when closed, connects one terminal of the operating coil of the hammer to the circuit conductor 6O through the electronic valve 21. The other terminal of the coil beingalready connected to circuit conductor 51, the valve transmits alternate current waves, that is, only current waves of the same polarity. to the operating coil. The current wave form is illustrated in Fig; 6.

The operation of the valve 21 is such that when the filament. is negative with respect to the plate, current is transmitted by the valve,

but when .the filament -is positive;with respect to the plate or anode, no current tra verses the valve. The valve may therefore be regarded as transmitting .positive waves or impulses.

Assuming the .core 27 to be .in the position illustratedin Figs. 1 and 2 when the trigger switch is closed, the first positive alternation or current wave will traverse the valve 21 1 and energize theoperating coil 26 to Vestab lisha magnetic flux field across the annular air gap between the laminations 334.. The core will be pulled backward toward the backstop 46. lVhenthe core reaches-the I, central part of the barrel the .positive-,alter nation or. current wave diminishes to zero value and the winding then-remains unenergizeduntil the next; positive alternation .begins. ,During the interval between-the posii 'tive waves, howeycnthe core. continues-its travel on itsuzo vv n n o mentumzor inertia, from the ,central-n egion; oiathe barrelmntil -e ee s the baeletene Att m e the second positive alternation-traverses the valve andthe' operating coil, andthe magnetic flux-field is reestablisliedacrosstlre airgap. The core is then ,pulled forward to strike the end of the tool shank toideliver a working blow .to the tool. The coil become's de-ene'rigized about thex i ne the core-reaches the middle region ofthe barrel and again the core'continues its travel during the interval until the coil is again energized. Such re ciprocating action of the core continues in synchronism' with the transmitted current magnetic'energy stored in the magnetic field by the-operating coil is translated into useful mechanical energy stored in the reciprocat ing core. In devices embodying movable contact members. considerable energy is'di'ssipated as heat. in the arc between such members. A valve of the type which I here employ, however, having no moving contact members, permits all energy stored'in the magnetic field to be utilized for useful'work. In the present system 'stationaryftermina'ls or electrodes are employed and "the conduct ing medium between them is periodically rendered conductive to'transmit current. i

In the system that is illustrated in Fig. 9, an electrolytic valve is employed instead of the electronic valve 21 illustrated in Fig. 1. When operationcf the hammer is desired, the trigger switch 33 is closed to energize the relay switch 55. The relay switch connects the hammer actuating coil in series vvit hthe electrolytic valve :65 to the-alternating current circuit'QO. The action of the electrolytic valve is substantially similar to that oitthe electron valve except that,.i nstead of entirely suppressing the negative current, a small negative 'cunrent is transmitted to the hammer, as illustrated in Fig-10. The

negative current transmitted is .merely sufficientrto neutralize any residual magnetismin the ,magnetic circuit of-the ;l1am-mer but is not sufiicient to influence the actuationofthe vcore to any great-extent. The electrolytic valve therefore transmits preponderating'ly unidirectional cur-rent impulses that act upon the core to acetuate it in synchronism with the current impulses. j V qW h h e :e y' &le. as with he elect pnicvalve, the adyantage of Stationary, non-arcing terminals .orelectrodes, 1-.is present. The electrolytic-valve also @errni'ts al-l oi-.the euergy goredin the magnetic field to expend itseLt-indoin'g useful work storing ene gy inithe core, instead." ct fwasting itself .as'lieatg 'j 21w 3.3.

- A mercury arc valveimay be employed in a manner similar to that in'wliicli the-electron valveiis used in thesystem illustrated in- Fig. 1. The mercury "valve-also con- -s ti tutes a control device which embodies ista tionar'y electrodes and a con'ductiIngmedi-um to transmitall energy stored in themagneti'c tfield. A simple system containing a mercury arcwalve is diagrammatically illustraited in Fig. ill. I The mercury arc valve is of-the usual form andeomprises two anodesi'i and 72, a cathode'73, an auxiliary anode 74, and'two mercury pool-s and'76 associated with the cathode 73 and the auxiliary anode 74, re-

spectively, all disposed'in a glass 'bulbf l' 'l'j.

A tilting magnet 78 operates when energized to tilt the rectifier bulb 77 to efi'ect'uiiomentary engagement between the mercury pools 7 5 and 76. iVhen the bulb resumes'its'normalposition and the mercury pools separate, an arc is estaiblishediietween them anda condition of acbivity'i's'establishe'd in -the bulb which promotes current conduction between the cathode 7-3 and the anodes'71 and 72. limiting resistor'79is disposed in circuit with the auxiliary anode 74 to limit the value of current that may traverse that circuit. An autotransformer'80 is provided to establish an artificial neutral point 81.

The trigger switch is provided with. an additional contact portion 83 to control the circuit of the tilting magnet 78.. As the trigger switch is moved toward the closed position, the contact 83 momentarily energizes the tilting magnet to tilt the bulb and establish 'ac'ondition of activityin the bulb. In the fully closed position, the bridging contact of the trigger "switch is in contact only with the fixed contacts controllin" the bulb circuit. The mercury vapor pro need by the arc, established between the pools of mercury, constitutes a stream or conducting medium between the anode and the respective cathodes, but will only conduct current whenthe anode 71 or 72 is positive with respect to the cathode 73.

Since the cathode 73 is connected to the artificial neutral point 81. the anodes 71 and 72 will alternately be positive and negative relative to the cathode.

WVhen the anode 71 is positive relative to the cathode, current is transmitted to, and traverses, the operating coil of the hammer to actuate the corein one direction or the other. -A current wave or impulse will be transmitted to the hammer each time the anode -71 is positive and the core will be reciprocated in synchronism with such impulses, as in the system illustrated in Fig. 1.

The continued operation of the mercury valve is dependent upon the maintenance of the condition of activity in the bulb. To sustain the active condition between the intervalsduring which current is transmitted to the hammer coil a reactor 82 is disposed in the'circuit of the anode 72. The current traversing the reactor circuit is sufficient to sustain the arc to maintain the condition of activity'in the bulb but is not of such character as to impose a load upon the transformer80. i

In the mercury valve, as in the electrolytic and the electron valve, the energy stored in the electromagnetic field of the hammer coil is transmitted to do useful work.

The operation of an electric valve in controlling the energization of the electric hammer is automatically controlled by the polarity of the electrodes and is thus electrical and automatic, as distinguished from arbitrary operation of mechanical rectifiers irrespective of variations in the operation of the core and, consequently, in the development of the magnetic field. The electrical valve transmits all energy stored in the magnetic field, whereas the mechanical rectifier permits a great portion of such energy to be wasted as heat in arcing between contact surfaces. The electric valve is more efiicient and economical, and requires less servicing and attention than the mechanical rectifier.

In the present system employing an electric valve, all energy derivable from the current waves is available for transformanm.-*-=-1zi':r;=.i energy to be stored in the reciprocating core. None is wasted in arcing.

The feature of a system of the described character, embodying the principles of my invention, is a single moving part during operation, viz, the core 27 that is moved back and forth in the bronze barrel. While the hammer is operating. the valve is stationary, the magnet switch is stationary and the trigger switch is stationary. The wear and tear incident to operation of a percussive tool are reduced to an absolute minimum in a system of the character herein described. The advantages of a system of this character are self evident.

In the example of 'my invention herein moie particularly illustrated, the airgap, between the longitudinally spaced pole tips 38, is disposed intermediate the ends of the 27, whatever its length,-passes the position of minimum length of air gap between it- '75 exciting winding 26; the reciprocating core' self and the field structure in the forward stroke or stroke in which it deliversimpact to the tool; similarly, 'the core passes .the position of minimum lengthof air gap be tween itself and the field structure on the return stroke; and the length'of the core is preferably such as at least completely to bridge the gap between the. aforesaid. longitudinally spaced pole tips 38. I

Oll

are due solely to the electricv valve, and are not dependent upon either mechanical switching mechanism or an unusual or particular wave form of the electroanotiveforce of the supply circuit.

My invention thus comprehends a method of and means for controlling a reciprocating motor, or other inductive translating de vice, by a system involving devices compris ing stationary electrodes between which the electrical conductivity is varied by electrical action to regulate the transmission of current in unidirectional or preponderatingly unidirectional impulses.

My invention further comprehends a sys: term for controlling a reciprocating motor, or other inductive translating device, whether requiring periodic impulse energization or not, so that all energy stored in the magnetic field of the motor or other translating device may be utilized to do useful work.

My invention is not limited to the ap- March 5, 1924;

Hmeiits mes-1151" be? HichWitifii seie a b ee ata et itii eereu Certain, of the subjectmatter herein dis: closed, particularly features and structure of the. reciprocating motor orl percu ss1ve 'tool per seyis not herein claimed, but IS ClZIImGd in my application Serial No. 6.97,053, filed I claim as mylinvention- V 1.. The method of operating a reciprocating motor .provided ,-Wit h a movable magnetizable member, which comprises scleetrn solely by. asyimnetrical electrical- COlIdUCiZIOD successive current} impulses. from a, ,source of Single Phase e l i'e i iefwr ze fi 1 1 1. fecting' .inovem'eiit of. said? magnetizable member by. 'tm(lulatory electro magnetism produced by said impnl sesrr, A v

2 The method of. operatingn; rec1procating i motor pr'oi ided vithl a movable; mag.- t 'zble. m m m wh h omp ses, s ec ing; .sole ly. 1,55 n-gear electrical conduct'ion: s'uc'cessiyef impulses from a source" of single gen-ge alternat ng; current, e e i g sued" i eum te ents;et efi .%'e ii i n b tl me e y 53mmee wmagfi isn.,p qd cee y a 3. ''The' 'methocl -ff6pe ting i 'eeiproeat: in T 6 e '3nr' ri's1edh h al'fi abls netiz able'inie her; which comprise-sf elect: x elr fii ewe-1 i w c -49a, e e t qlrt enfi impulses, .fiQL soui'iiefoisinglei 311 r" ting current,

i a" fl c'tuetm saidunagnetizable member in each direction;

7. The combination with a reciprocating motor comprising an actuatingwinding and a reciprocating nmgnetixable member moved in both directions by said winding, of a source of single phase alternating current, and an electric valve in circuit with said; source and said winding and serving as the sole means for selectin current impulse; from said source for energixation of said winding, whereby alternate impulses so sclectcd move said magnctizable member suecessively in one direction, and the intervenlllg selected impulees move said magnetizable member successively in opposite direction. I

8., 'llie combination with a reciprocating mot-or comprising eiectro-nmgnetic lieldproducing means. and -iagnetizablc member reeiprccated thereby, of a source of single phase alternating current, and a tllCl'-' mionic valve in circ'. said '1i1eans.and serving as sole means for.

t with said source and contiolli'rig, energizatlon of; saidftield-pro ;ber reciprocated.thereby, of a source of .gle phase alternating current, and;a ther? Inionic valve in circuit with said source and said meansand set-yin; as meanslfor con trolling energization of said field-producing means by succ essive LlDldll'CCtlOllzll current move ents ','of, said magnetizable member all in each direction. 10

combination with a reciprocating om'prismgf electromagnetic fieldro'clulngQ means and a magnetizable memmpu l s e s. "from said source: for, effecting erfrecipro ca'tetl-thereby, o'f a'source of sine gIeLph'ase alternating current, asymmetricah 1y co'iiductingmeans in, circuit I ivith said 4 Qii source and said means and serving as.means I iii'tit 'zihleimag fifor"selecting ci'irrent'iinptdses from said source"for energization of said first named ing lsblelfliy' asymmetriefii'eie tfieir contluc= meanjs to effect movement oi said magnetiz- 'fi om a. abliinenib'er, and'a' t'ool' reeeiving,tlie imsourc'e" df'si'i i'gl ph ls e altlil rm u1'jrent pactof'said'magnetizable member, said mag: producing-a fluctuating'elebtro magnetic netizable member. magnetically. returned; fieldf'bysaid'irnpnlssflv axld efiecting movefrom' itsjimpac't stroke by energrzat on of ments fof s'aid magr'ietii zablemeiiibei' in both .saictfirst 'named means by current.traverse directiOns-bysaitrfie d ing said a'synnnct-rieally conducting means 6." The c0mbination"-'with aireciprocating motor comprising anact'u'atin'g winding and nmglnetizable member :for delivering impact tion successive current en a ing 11. The combination with n tool, of. a.

I, a reciprocating magnetizable member, ofa thereto, and means tor euecting return or source of single phase alternating current, said magnetizable member it'rom impacting and an electric Valve in circuit? with said position comprising aseinree of single phase source and said \vindinghn'd"serving-as the alternating current, a winding; for producsole means for selecting current impulses ing a field lor actnatingsaid iiiagne't-izable from said source for energi'zation of said member for ell'ectingits return stroke magwinding to effect magnetically movement of netically and an electric valve in circuit and an electrlc valve in circuit with said source and said winding and serving as means for selecting current impulses from said source for energization of said winding to effect movement of said magnetiz able core past position of minimum air gap length.

13. The combination with a reciprocating motor comprising a field winding, a magnetizable core reciprocatecl thereby axially thereof, and magnetizable field members forming an air gap with respect to which said ma netizable core is movable, of a source of single phase alternating current, an electric valve in circuit with said source and said winding and serving as means for selecting current impulses from said source for energization of said winding to effect magnetically movement of said magnetizable core in each direction past position of minimum air gap length, and a tool receiving the impact of said core after its movement past said position.

14. The combination with a reciprocating motor comprising a field Winding, a magnetizable core reciprocated thereby axially thereof, and magnetizable field members forming an air gap with respect to which said magnetizable core is movable, of a source of alternating current, an electric valve in circuit with said source and said winding and serving as means for selecting current impulses from said source for energization of said winding, and a tool receiving impact of said core, energization of said winding serving to actuate said core on its return stroke past position of minimum air gap length.

15. The combination with a reciprocating motor comprising a field winding, a magnetizable core reciprocate'd thereby axially thereof, and magnetizable field members forming an air gap with respect to which said magnetizable core is movable, said core having a length inthe direction of its movement sufiicient substantially completely to bridge said air gap, of a source of alternating current, and an electric valve in circuit with said source and said winding and serving as means for selecting current impulses from said source for energization of said winding to effect movement of said magnetizable core past position of minimum air ga length.- r

n' testimony whereof, I have hereunto subscribed my name this 29th day of February, 1924.

CARL S. WEYANDT. 

